Serum/plasma tests
Hormones
Steroid Hormones
Androstenedione
Bioavailable testosterone
Cortisol
DHEA-S
Dihydrotestosterone (DHT) (TOS)
Estradiol
Estradiol-HRT
17-OH progesterone (TOS)
Pregnenolone
Progesterone
Testosterone
Peptide Hormones
Follicle Stimulating Hormone (FSH)
Insulin (TOS)
Luteinizing Hormone (LH)
Secretin (TOS)
Sex Hormone Binding Globulin (SHBG)
Thyroid Stimulating Hormone (TSH)
Vasoactive Intestinal Polypeptide (VIP) (TOS)
Other Hormones
Free Triiodothyronine (FT3)
Free Thyroxine (FT4)
Triiodothyronine (T3)
Thyroxine (T4)
Other

TOS - To be offered shortly


Tests › Serum/plasma tests › Hormones › Steroid Hormones › Bioavailable testosterone

Bioavailable testosterone

Significance
Testosterone circulates in the body mostly bound to sex hormone binding globulin, non-specifically bound to albumin, and in free form (about two percent is unbound). The free form and the fraction bound to albumin are also collectively referred to as the ‘bioavailable fraction’ and this fraction is accepted to be more clinically relevant than the total testosterone.

Analysis
Determination of bioavailable testosterone is performed by radioisotope equilibration followed by precipitation of SHBG bound fraction.

Patient Preparation
Morning specimen is preferred.

Specimen requirements
Serum specimen - from a plain redtop or a redtop gel (tiger top) tube. Separate serum from cells within 60 min if a plain redtop tube is used. Provide patient age and gender. Minimum volume required is 1 mL. Specimen should be kept refrigerated where possible.

Shipping Instructions
Ship specimen at ambient temperatures. For long distance shipping, ship with ice packs.

Additional information